pub struct Breakfast { // 在结构体里边，数据的pub和pri都是默认pri的，我们需要自己加pub来使其公有
    pub toast: String,
    seasonal_fruit: String,
}

pub enum Appetizer{
    Soup,
    Salad,
}

impl Breakfast {
    pub fn summer(toast : &str) -> Breakfast {
        Breakfast {
            toast : String::from(toast),
            seasonal_fruit : String::from("peaches"),
        }
    }
}
